Institutional Animal Care and Use Committee

Policy #0105

“Care of Animals with Experimental Tumors” 

Animals that are expected to develop tumors as a result of experimental manipulation, genetic predisposition, or injection of tumor cells must be closely monitored to avoid any pain or suffering beyond that which is essential to accomplish the investigator’s stated experimental goals. 

Any animals expected to develop tumors must be visually observed at least once a week by the Principal Investigator (PI) or his/her designee. Any animal which has evidence of tumor growth (visible, palpable, behavioral, or by test results, such as fecal occult blood) must be monitored on a regular basis as described in the approved animal use protocol.   

Unless there is scientific justification to the contrary, an animal must be sacrificed, or the tumor mass removed surgically, if one or more of the following criteria is met: 

  • An external or palpable tumor has a maximum diameter greater than: 
    • 1cm -  mice, small rats, gerbils, hamsters 
    • 2cm -  large rats (>200g), guinea pigs  
    • 3cm -  adult rabbits 
  • The tumor mass interferes with the animal’s ability to move or to obtain food and water 
  • The tumor or skin overlying the tumor is ulcerated or necrotic (discolored) 
  • The tumor shows evidence of hemorrhage 

Unless there is scientific justification to the contrary, an animal must be sacrificed if one of the following criteria are met: 

  • Loss of 20-25% of pre-tumor adult body weight (excluding the estimated weight of the tumor) and/or loss of body condition (wasting) 
  • Loss of appetite, lethargy, reluctance or inability to move, hunched posture, ruffled fur 
  • Evidence of internal hemorrhage or anemia (i.e., frank or occult fecal or urinary bleeding; pale appearance of eyes, ears, or mucous membranes; measured hematocrit <20%; abdominal distension with frank blood on abdominal tap; extreme weakness) 
  • Evidence of pain (excessive licking or chewing at the tumor location; vocalization on palpation; grinding teeth), unless symptoms are relieved by analgesics 

Surgical removal or sacrifice must be performed in a timely manner, within twenty-four (24) hours of the criteria being met. Such animals must be euthanized promptly by the PI’s staff and must not be tagged and left for Institute for Animal Studies’ staff to sacrifice. 

Any exceptions to these guidelines must be scientifically justified and approved by the Institutional Animal Care and Use Committee as part of the PI’s animal use protocol prior to the start of any study. 

Approved:  5/16/2001 

Reviewed and Reapproved: 6/15/2011; 12/17/2013 

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